[Value of combined coronary angioplasty and coronary angiography]. / Intérêt de l'angioplastie coronaire dans le même temps que la coronarographie.

Combined coronary angioplasty and coronary angiography is performed in most catheter laboratories and has become a routine procedure. The aim of this study was to assess its clinical results and economic value. This was a retrospective monocenter study performed over an 11 year period (1990-2000) which included 2,727 patients requiring coronary angioplasty after coronary angiography. The angioplasty procedure was performed at the same time as angiography (combined, n = 1,809) or after angiography (deferred, n = 631). Patients admitted for acute coronary syndromes not stabilised by pharmacological interventions were excluded from the study. The comparison of these two modes of angioplasty was based on primary success rates, complications, duration of hospital stay and hospital costs. The combined procedure was used progressively more frequently over the study period, increasing from 54% to 88% in 2000. The hospital clinical results (Success and complication rates) were comparable in the two groups. The predictive factors of failure were the year of the angioplasty procedure and occlusive lesions on multivariate analysis. The combined procedure was associated with a shorter hospital stay than deferred angioplasty (8.2 +/- 6.1 days versus 15.0 +/- 8.0 days, p = 0.0001) and with lower costs. The authors conclude that combined coronary angiography-angioplasty is as effective and as safe as deferred angioplasty. It is associated with a shorter hospital stay and lower hospital costs.

Relations of platelet Ca2+ handling and membrane microviscosity to vascular tone and restenosis after angioplasty in human coronary artery.

This study was designed to assess whether platelet Ca2+ handling or membrane microviscosity could be considered as indexes of vascular tone, or could help to predict an increased risk of restenosis after coronary angioplasty. Vascular tone was quantified in 21 patients with stable angina by the vasodilator response to sin-1 intracoronary injection in the reference coronary segment and by the importance of the acute recoil after angioplasty in the narrowed segment. The degree of restenosis was quantified by coronary angiography 6 months later. Individual values of relative sin-1-induced changes in the reference coronary diameter were positively correlated with cytosolic Ca2+ concentration in unstimulated platelets, irrespective of the extracellular Ca2+ concentration (p < 0.01). This relationship was also observed with the thrombin-evoked Ca2+ changes, measured in the absence of a Ca2+ influx (p = 0.01). No relationship was found between sin-1-induced coronary changes and membrane microviscosity evaluated by TMA-DPH and DPH anisotropies or platelet volume, or between degree of acute recoil and platelet characteristics. In conclusion, platelet Ca2+ reflects the vasodilating efficacy in response to sin-1, but cannot help to predict restenosis after coronary angioplasty.

[Analysis of frequency-dependence of ventricular repolarisation by the Holter method in young adults. Influence of the autonomic nervous system on the rate-dependence of QT]. / Analyse de la fréquence-dépendance de la repolarisation ventriculaire par méthode Holter chez l'adulte jeune. Influence du système nerveux autonome sur la fréquence-dépendance de QT.

UNLABELLED: Adaptation of ventricular repolarization duration to heart rate provides additional information to the static duration of QT interval. METHODS: QT/RR relation and his slope were determined using 24-hour ECG recordings from 17 young male normal volunteers (mean age: 22 +/- 3 years). In order to determine the influence of the autonomic nervous system on the rate-dependence of QT, the authors compared the slopes obtained from recordings during the day and the night. Then, the respective rate-dependences of the entire QT interval (QTe) and its initial subdivision (QTa) and their correlations with parameters of heart rate variability were studied. RESULTS: the QTa/RR and QTe/RR relations were constantly linear, with very significant regression coefficients. The daytime QTa/RR and QTe/RR slopes were significantly steeper than the nighttime ones (0.138 +/- 0.035 vs 0.108 +/- 0.040, p < 0.05 for QTe/RR, 0.160 +/- 0.069 vs 0. 108 +/- 0.055, p < 0.01 for QTa/RR). The early part of QT showed a stronger rate-dependence than the global QT, but only at daytime (0.160 +/- 0.069 vs 0.138 +/- 0.035, p < 0.05). No correlation was found between rate dependences and heart rate variability parameters. CONCLUSION: the authors demonstrate, from ambulatory ECG recordings, the influence of the autonomic nervous system on the rate-dependence of ventricular repolarization in normal young adults, and a difference in rate-dependence between the entire QT interval and its initial part QTa, due to differences in autonomic nervous system tone. This heterogeneity should be taken to account in the study of pathological changes or drugs effects on ventricular repolarization.

[Dynamics of ventricular repolarisation]. / Dynamique de la repolarisation ventriculaire.

The clinical value of assessing the QT interval is obvious as it is a marker of ventricular depolarisation and repolarisation and it allows identification of clinical situations carrying a high risk of ventricular fibrillation and sudden death. Until the last few years, analysis of ventricular repolarisation was based on analysis of conventional surface electrocardiography. Technical difficulties explain the limits of our knowledge of the dynamics of ventricular repolarisation. This situation is beginning to change rapidly by computerised analysis of Holter monitoring, opening up a particularly complex and important field of research. The duration of the QT interval depends on different factors, especially changes in electrolyte balance, effects of certain drugs, and changes in heart rate and autonomic nervous system tone. The difficulty resides in selecting the pertinent data in order to study separately the effects of heart rate and those of the autonomic nervous system. The initial results show that this analysis provides important information for diagnosis and probably prognosis, on the status of the myocardium and the action of the autonomous nervous system. They require confirmation and validation on larger series of patients with different pathological conditions.

Heart rate and heart rate variability in normal young adults.

INTRODUCTION: The relationships between heart rate (HR) and HR variability (HRV) are not simple. Because both depend on the autonomic nervous system (ANS), they are not independent variables. Technically, the quantification of HRV is influenced by the duration of the cardiac cycles. The complexity of these relationships does not justify ignoring HR when studying HRV, as frequently occurs. METHODS AND RESULTS: Using spectral and nonspectral methods, the HR and various normalized and non-normalized indices of HRV were studied in 24-hour recordings of a homogeneous cohort of seventeen 20-year-old healthy males. The HR-HRV relationships were appraised by analyzing the same data in two different ways. The 24 mean hourly values provide consistent information on the circadian behavior of the indices, while the average 24-hour individual data show a wide spectrum of normality. Combined approaches allow assessment of the direct impact of RR interval on HRV evaluation. The correlations between HR and normalized indices of HRV are weaker in 24-hour individual data than in pooled hourly data of the same individuals. These correlations are close to 1 in the latter case, which does not mean that measuring HRV is simply another method of evaluating HR, but that normal physiology supposes a harmonious behavior of the various indices. When considered individually without normalization, the specific indices of vagal modulation (high-frequency band of the spectrum, short-term HR oscillations of the nonspectral analysis) consistently increase at night and diminish during the day. However, the low-frequency power, which supposedly reflects sympathetic influences, also increases at night, whereas more logically the longer HR oscillations would predominate during the day. Moreover, the selective analysis of HR oscillations during HR acceleration or decrease indicates that their behavior differs accordingly. CONCLUSION: We recommend that closer attention be paid to the complex relationships between HR and HRV. The strong correlations found in healthy subjects may reflect either the physiological harmony of ANS functions or simple redundancy. Their tendency to deteriorate in diseased hearts suggests that redundancy is not the cause and that abnormalities of ANS functions are not demonstrated by HRV analysis alone.